Scenario:

1. Make sure MAFFT external tool is set up.
2. Open an alignment that contains a sequence with name that has non-ASCII characters (e.g. Russian).
3. Click "Align sequence to this alignment" button on the toolbar and select some appropriate sequence.
   Expected result: the sequence has been aligned to the alignment.
   Current result: an error occurs, the following notification is pop up:

   'Align sequences to alignment task' task failed: Subtask {Align sequences to alignment task} is failed: Document is empty.
   

   In the "TRACE" category of the log there may be messages like:

   MAFFT: Distance 0-230 is strange, 13.304991.
   

The sequences should be temporarily renames when MAFFT is run. Note that a similar feature is used when multiple sequence alignment is done.

Check also other tasks: pairwise alignment, building a tree, etc.